On 09/25/2016 09:29 PM, Josh Triplett wrote: > On Sun, Sep 25, 2016 at 09:03:07PM +0200, Michael Kerrisk (man-pages) wrote: >> On 09/04/2016 07:11 AM, Josh Triplett wrote: >>> On Sun, Sep 04, 2016 at 04:30:44PM +1200, Michael Kerrisk (man-pages) wrote: >>>> [CC += Josh] >>>> >>>> Josh, I know you were submitting patches relate to the clone() TLS argument a >>>> while back. Could you comment on this patch proposal below (also >>>> https://bugzilla.kernel.org/show_bug.cgi?id=118241 is relevant). >>> >>> Sure. >>> >>>> On 08/24/2016 03:06 PM, Keno Fischer wrote: >>>>> The prototype for the system call was added in 81f10dad, but looking at the >>>>> kernel's fork.c, I believe the relevant definition is >>>>> >>>>> SYSCALL_DEFINE5(clone, unsigned long, clone_flags, unsigned long, newsp, >>>>> int __user *, parent_tidptr, >>>>> int __user *, child_tidptr, >>>>> unsigned long, tls) >>>>> >>>>> so the last argument is the tls argument, not a pt_regs argument. >>>>> I stumbled upon this while trying to understand CLONE_SETTLS, so I expanded >>>>> that description a little to cover other architectures. >>> >>> This description and patch looks correct to me. >>> Reviewed-by: Josh Triplett <josh@xxxxxxxxxxxxxxxx> >> >> Thanks, Josh. >> >>> Ideally, I'd suggest a follow-up patch to improve the prototypes for the >>> various architectures. Rather than saying "x86 looks roughly this way, >>> on these architectures swap these arguments, on these architectures >>> ...", I'd suggest explicitly giving each of the four prototypes (normal, >>> CONFIG_CLONE_BACKWARDS, CONFIG_CLONE_BACKWARDS2, >>> CONFIG_CLONE_BACKWARDS3) and the corresponding architectures. >> >> I applied the patch below. Okay? > > Mostly looks good, but one comment below. > >> diff --git a/man2/clone.2 b/man2/clone.2 >> index 5c1e301..26c6b30 100644 >> --- a/man2/clone.2 >> +++ b/man2/clone.2 >> @@ -54,11 +54,7 @@ clone, __clone2 \- create a child process >> .BI " /* pid_t *" ptid ", void *" newtls \ >> ", pid_t *" ctid " */ );" >> >> -/* Prototype for the raw system call */ >> - >> -.BI "long clone(unsigned long " flags ", void *" child_stack , >> -.BI " int *" ptid ", int *" ctid , >> -.BI " unsigned long " newtls ); >> +/* For the prototype of the raw system call, see NOTES */ >> .fi >> .SH DESCRIPTION >> .BR clone () >> @@ -821,16 +817,58 @@ arguments of the >> .BR clone () >> wrapper function are omitted. >> Furthermore, the argument order changes. >> -The raw system call interface on x86 and many other architectures is roughly: >> +In addition, there are variations across architectures. >> + >> +The raw system call interface on x86-64 and some other architectures >> +(including sh, tile, and alpha) is roughly: >> + >> .in +4 >> .nf >> +.BI "long clone(unsigned long " flags ", void *" child_stack , >> +.BI " int *" ptid ", int *" ctid , >> +.BI " unsigned long " newtls ); >> +.fi >> +.in >> + >> +On x86-32, and several other common architectures >> +(including score, microblaze, ARM, ARM 64, PA-RISC, arc, Power PC, xtensa, >> +and MIPS), >> +.\" CONFIG_CLONE_BACKWARDS >> +the order of the last two arguments is reversed: >> >> +.in +4 >> +.nf >> .BI "long clone(unsigned long " flags ", void *" child_stack , >> +.BI " int *" ptid ", unsigned long " newtls , >> +.BI " int *" ctid ); >> +.fi >> +.in >> + >> +On the cris and s390 architectures, >> +.\" CONFIG_CLONE_BACKWARDS2 >> +the order of the first two arguments is reversed: >> + >> +.in +4 >> +.nf >> +.BI "long clone(void *" child_stack ", unsigned long " flags , >> .BI " int *" ptid ", int *" ctid , >> .BI " unsigned long " newtls ); >> +.fi >> +.in >> + >> +On the microblaze architecture, >> +.\" CONFIG_CLONE_BACKWARDS3 >> +an additional argument is supplied: > > This mentions microblaze twice: one in CONFIG_CLONE_BACKWARDS and again > here. Ahh -- the furst mention was a mistake. Fixed now. Thanks for spotting that. > And I don't see IA-64 mentioned anywhere. It was already covered by existing text in the page. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
